Identical and Nonidentical Twins: Risk and Factors Involved in Development of Islet Autoimmunity and Type 1 Diabetes

OBJECTIVE

There are variable reports of risk of concordance for progression to islet autoantibodies and type 1 diabetes in identical twins after one twin is diagnosed. We examined development of positive autoantibodies and type 1 diabetes and the effects of genetic factors and common environment on autoantibody positivity in identical twins, nonidentical twins, and full siblings.

RESEARCH DESIGN AND METHODS

Subjects from the TrialNet Pathway to Prevention Study (N = 48,026) were screened from 2004 to 2015 for islet autoantibodies (GAD antibody [GADA], insulinoma-associated antigen 2 [IA-2A], and autoantibodies against insulin [IAA]). Of these subjects, 17,226 (157 identical twins, 283 nonidentical twins, and 16,786 full siblings) were followed for autoantibody positivity or type 1 diabetes for a median of 2.1 years.

RESULTS

At screening, identical twins were more likely to have positive GADA, IA-2A, and IAA than nonidentical twins or full siblings (all P < 0.0001). Younger age, male sex, and genetic factors were significant factors for expression of IA-2A, IAA, one or more positive autoantibodies, and two or more positive autoantibodies (all P ≤ 0.03). Initially autoantibody-positive identical twins had a 69% risk of diabetes by 3 years compared with 1.5% for initially autoantibody-negative identical twins. In nonidentical twins, type 1 diabetes risk by 3 years was 72% for initially multiple autoantibody-positive, 13% for single autoantibody-positive, and 0% for initially autoantibody-negative nonidentical twins. Full siblings had a 3-year type 1 diabetes risk of 47% for multiple autoantibody-positive, 12% for single autoantibody-positive, and 0.5% for initially autoantibody-negative subjects.

CONCLUSIONS

Risk of type 1 diabetes at 3 years is high for initially multiple and single autoantibody-positive identical twins and multiple autoantibody-positive nonidentical twins. Genetic predisposition, age, and male sex are significant risk factors for development of positive autoantibodies in twins.

Low-Dose Anti-Thymocyte Globulin (ATG) Preserves β-Cell Function and Improves HbA1c in New-Onset Type 1 Diabetes

OBJECTIVE

A pilot study suggested that combination therapy with low-dose anti-thymocyte globulin (ATG) and pegylated granulocyte colony-stimulating factor (GCSF) preserves C-peptide in established type 1 diabetes (T1D) (duration 4 months to 2 years). We hypothesized that 1) low-dose ATG/GCSF or 2) low-dose ATG alone would slow the decline of β-cell function in patients with new-onset T1D (duration <100 days).

RESEARCH DESIGN AND METHODS

A three-arm, randomized, double-masked, placebo-controlled trial was performed by the Type 1 Diabetes TrialNet Study Group in 89 subjects: 29 subjects randomized to ATG (2.5 mg/kg intravenously) followed by pegylated GCSF (6 mg subcutaneously every 2 weeks for 6 doses), 29 to ATG alone (2.5 mg/kg), and 31 to placebo. The primary end point was mean area under the curve (AUC) C-peptide during a 2-h mixed-meal tolerance test 1 year after initiation of therapy. Significance was defined as one-sided P value < 0.025.

RESULTS

The 1-year mean AUC C-peptide was significantly higher in subjects treated with ATG (0.646 nmol/L) versus placebo (0.406 nmol/L) (P = 0.0003) but not in those treated with ATG/GCSF (0.528 nmol/L) versus placebo (P = 0.031). HbA_1c was significantly reduced at 1 year in subjects treated with ATG and ATG/GCSF, P = 0.002 and 0.011, respectively.

CONCLUSIONS

Low-dose ATG slowed decline of C-peptide and reduced HbA_1c in new-onset T1D. Addition of GCSF did not enhance C-peptide preservation afforded by low-dose ATG. Future studies should be considered to determine whether low-dose ATG alone or in combination with other agents may prevent or delay the onset of the disease.

A Type 1 Diabetes Genetic Risk Score Predicts Progression of Islet Autoimmunity and Development of Type 1 Diabetes in Individuals at Risk

OBJECTIVE

We tested the ability of a type 1 diabetes (T1D) genetic risk score (GRS) to predict progression of islet autoimmunity and T1D in at-risk individuals.

RESEARCH DESIGN AND METHODS

We studied the 1,244 TrialNet Pathway to Prevention study participants (T1D patients' relatives without diabetes and with one or more positive autoantibodies) who were genotyped with Illumina ImmunoChip (median [range] age at initial autoantibody determination 11.1 years [1.2-51.8], 48% male, 80.5% non-Hispanic white, median follow-up 5.4 years). Of 291 participants with a single positive autoantibody at screening, 157 converted to multiple autoantibody positivity and 55 developed diabetes. Of 953 participants with multiple positive autoantibodies at screening, 419 developed diabetes. We calculated the T1D GRS from 30 T1D-associated single nucleotide polymorphisms. We used multivariable Cox regression models, time-dependent receiver operating characteristic curves, and area under the curve (AUC) measures to evaluate prognostic utility of T1D GRS, age, sex, Diabetes Prevention Trial-Type 1 (DPT-1) Risk Score, positive autoantibody number or type, HLA DR3/DR4-DQ8 status, and race/ethnicity. We used recursive partitioning analyses to identify cut points in continuous variables.

RESULTS

Higher T1D GRS significantly increased the rate of progression to T1D adjusting for DPT-1 Risk Score, age, number of positive autoantibodies, sex, and ethnicity (hazard ratio [HR] 1.29 for a 0.05 increase, 95% CI 1.06-1.6; P = 0.011). Progression to T1D was best predicted by a combined model with GRS, number of positive autoantibodies, DPT-1 Risk Score, and age (7-year time-integrated AUC = 0.79, 5-year AUC = 0.73). Higher GRS was significantly associated with increased progression rate from single to multiple positive autoantibodies after adjusting for age, autoantibody type, ethnicity, and sex (HR 2.27 for GRS >0.295, 95% CI 1.47-3.51; P = 0.0002).

CONCLUSIONS

The T1D GRS independently predicts progression to T1D and improves prediction along T1D stages in autoantibody-positive relatives.

Central nervous effects of leptin and insulin on hippocampal leptin and insulin receptor expression following a learning task in Wistar rats

Insulin and leptin are well known to be involved in the regulation of food intake and body weight. Recent studies have suggested that both hormones may also affect memory and learning processes. We explored whether the intrahippocampal administration of insulin or leptin improved spatial memory formation in rats following a radial maze task and whether the insulin and leptin receptor expression in different areas of the hippocampus was affected. Animals without a learning task were also investigated in order to differentiate between the influence of spatial learning and hormone application on receptor expression. Spatial memory formation was found unaltered following the different applications. The application of insulin increased the expression of the long form of the leptin receptor in the Ammon's horn and dentate gyrus region of the hippocampus in the learning group only. These data clearly show that learning is a prerequisite for the effect of insulin on leptin receptor expression.

Effects of tenuiorin and methyl orsellinate from the lichen Peltigera leucophlebia on 5-/15-lipoxygenases and proliferation of malignant cell lines in vitro

The orcinol derivatives tenuiorin (1) and methyl orsellinate (2) were identified as active components of an extract from the lichen Peltigera leucophlebia (Nyl.) Gyeln. showing in vitro inhibitory activity against 15-lipoxygenase from soybeans. The compounds were subsequently tested for in vitro activity against 5-lipoxygenase from porcine leucocytes and proved to be moderately active, with IC50 values of 41.6 microM and 59.6 microM respectively. Tenuiorin is a known constituent of several Peltigera species but has not previously been isolated from P. leucophlebia. As correlation between 5-lipoxygenase inhibition and antiproliferative effects has earlier been witnessed for related lichen metabolites, tenuiorin and methyl orsellinate were further tested for antiproliferative activity on cultured human breast (T-47D)-, pancreatic (PANC-1)- and colon (WIDR) cancer cell lines. The monomeric methyl orsellinate exhibited no detectable antiproliferative activity whereas the trimeric tenuiorin caused moderate/weak reduction in [3H]-thymidine uptake of the pancreatic- and colon cancer cells, with ED50 values of 87.9 and 98.3 microM respectively.

Analytical and pharmacological investigation of Ocotea bullata (black stinkwood) bark and leaves

Ocotea bullata (Lauraceae), one of the top-ten traditional medicinal plants used in KwaZulu-Natal, is close to extinction through high demand and destructive harvesting methods. The stem bark is traditionally used to cure headaches, urinary disorders and stomach problems. Substitution of leaves for bark provides a possible resource management solution for this threatened medicinal plant. One aim of this study was to compare the chemical composition of O. bullata leaves and bark using TLC, HPLC and GC-MS analysis. The characteristic analytical fingerprints of leaf and bark extracts showed great similarities. A second aim was to investigate the pharmacological properties of O. bullata as a remedy against headaches. Leaf and bark extracts were tested in terms of cyclooxygenase-1 and 5-lipoxygenase inhibition. Extracts from the bark exhibited moderate inhibitory activity in both test systems. Extracts from fresh leaves were superior to bark extracts in terms of their in vitro inhibitory activity against cyclooxygenase-1 and 5-lipoxygenase. Volatiles obtained from n-hexane extracts of leaves and bark showed better inhibitory activity towards cyclooxygenase-1 and especially towards 5-lipoxygenase than the original n-hexane extracts. Volatiles were therefore recognized as one of the main active principles in O. bullata with regards to the anti-inflammatory properties of this medicinal plant. This lends support to the traditional usage of O. bullata bark as an inhalant or snuff.

Stereostructure and anti-inflammatory activity of three diastereomers of ocobullenone from Ocotea bullata

A novel diastereomer of ocobullenone. designated as sibyllenone, was isolated from the stem bark of mature Ocotea bullata in the course of a search for anti-inflammatory compounds from this plant. The stereostructure was established by X-ray crystallography and corroborated by NOESY analysis. Ocobullenone, obtained previously, was re-isolated and crystallised successfully for X-ray analysis, thus making possible an accurate spatial comparison of ocobullenone, iso-ocobullenone and the new stereoisomer. Tested pharmacologically for cyclooxygenase-1 and 2, and 5-lipoxygenase inhibition, sibyllenone was the only compound from O. bullata which showed good inhibitory activity towards 5-lipoxygenase.

Automated counting of nuclei in series of conventional liver sections to differentiate hypertrophy and hyperplasia

A method based on image analysis and applicable in pharmacology and toxicology is described that has been designed to meet the statistical requirements for the determination of liver hypertrophy or hyperplasia. An algorithm has been developed to detect and count fluorescent nuclei in Feulgen-stained liver sections (12,500 to 25,000 nuclei or 170 to 350 fields of observation per section within 2-4 hr) by means of fully automatic image analysis with the Leitz Texture Analysis System (TAS) (up to 23 sections in series on the microscope stage). The applicability of this method to conventionally derived, formaldehyde-fixed, tissue sections has been tested on 3-microns sections cut from archived paraplast blocks of already diagnosed materials. Alterations in the liver induced by eight different compounds administered perorally for 28 days to rats have been studied. The morphometric results were found to be specific for a given compound and revealed reproducible and statistically significant dose dependencies of hypertrophy or hyperplasia, or both. Increased frequencies of mitotic figures observed by eye correlated reasonably well with the morphometrically determined hyperplasia, but many hyperplastic livers revealed no mitotic figures. By contrast, the histological diagnoses of an increased degree of hypertrophy were only poorly correlated with the morphometric determinations and, in many instances, were made in livers showing no decrease in the frequency of nuclei. On the other hand, the results from electron microscopy agreed well with the corresponding morphometric analyses: in cases with predominant hypertrophy the proliferation of the smooth endoplasmic reticulum was distinct or striking, or the peroxisomes were altered and increased in number, whereas no obvious ultrastructural changes were seen in cases of morphometrically exclusive hyperplasia.

Changes in nutritional quality of food in catering

Three main parameters influence the nutritional quality of food preparation: the choice of raw materials, the recipe and composition of a meal, and the preparation process. In catering systems the temperature and time history during preparation and distribution, i.e. systems like cook-chill, cook-freeze, or warm-holding, need particular attention with regard to some sensitive nutrients, e.g. vitamins C, B1, folic acid. If the main parameters and influencing factors as described are taken into account, it should not be difficult to produce food in catering with high nutritional quality.

[Physical preservation of food]

Physical preservation procedures are mostly aimed at prolonging the durability of foods by slowing down or repressing the spoilage mechanisms by the alteration of relevant parameters. Of these mechanisms of microbiological, enzymatic, chemical and mechanical type, especially the first-named are dealt with. Growth and multiplication of micro-organisms can be influenced by temperature, water activity and high-energy radiation. Depending on the susceptibility to deterioration of the products and the intensity of the processes based on these parameters, different degrees of durability are obtained. Micro-organisms are killed by the application of high temperatures in conjunction with the treatment times required in a given case. Relatively mild treatments affect only the vegetative forms (pasteurization), whereas more aggressive treatments are required to kill spores as well (sterilization). Recontamination of the products which were subjected to the two procedures must be avoided. Pasteurized foods require additional cold storage to prevent the spores from sprouting. Low temperatures reduce and repress the growth of micro-organisms (refrigeration) or prevent any activity of the micro-organisms (deep-freezing). The latter deprives the micro-organisms of the water they need for their growth. The same principle applies to another method of preservation where so much water is extracted from the product that the residual humidity no longer allows the micro-organisms to be active (drying). Ionising radiation can be used to reduce a potential risk to hygiene, to influence physiological processes, to control insects and to lengthen the durability of fresh food in the short term. Finally optimum product quality can be maintained by combining various procedures. If such methods cope with controlling the microbiological situation, attention must nevertheless be given to the other spoilage mechanisms as well, as they may prove to be limiting factors with respect to product quality.